Handle any missing properties for actions

Update getting a property value from the zone's cache to throw an
exception when not found. Handle these exceptions appropriately for each
action where it gets each property value of a group.

Change-Id: Icbc0b04f492d3680de77dbe3f27cabf7504ce6b4
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/control/zone.hpp b/control/zone.hpp
index 32707cb..a56b1c7 100644
--- a/control/zone.hpp
+++ b/control/zone.hpp
@@ -114,7 +114,7 @@
                                      const std::string& property)
         {
             return sdbusplus::message::variant_ns::get<T>(
-                    _properties[object][interface][property]);
+                    _properties.at(object).at(interface).at(property));
         };
 
         /**